An Electrical Micro-Generator

An electrical micro-generator might provide electric power for portable microscale devices. At a modern power station, high pressure fluids (water, steam, or gas) are dashed against turbine blades, thus turning a shaft which cranks out electricity. At an MIT lab, all of this is done on a centimeter-size scale. At an upcoming meeting of the AVS Science and Technology Society in Baltimore, Carol Livermore will describe a micromotor with a 4-mm rotor which puts out 20 milliwatts of power, far more power than any other existing rotating micromotor. The motor may be incorporated into a microscale gas turbine generator. This is, in effect, a tiny jet engine: air and gas mix in a small combustion chamber and the resultant explosion powers the turbine (see figure). The MIT researchers expect that soon the output will be at the level of 300 volts, and 1 watt of mechanical power or 0.5 watt of electrical power. The device might not yet be as compact as the best micro-batteries currently available, but it will be able to do what batteries cannot, namely supply power over long periods. (Paper MM-TuA3, Carol Livermore, 617-253-6761; meeting will be held November 2-7; visit website; background article)